Home-field advantage is important in any sport. The benefits include favorable cheers, a cushy locker room, no travel, a sea of fans, and a familiar climate. The gain that a home team gets is widely recognized and is treated accordingly by having an even amount of home and away games. However, some home-field situations seem unfair or even unsafe.
The Buffalo Bills experienced the losing end of home-field advantage in their third game of the season. Playing in Miami, the Bills lost six of their starters to heat-related injuries and many more were slowed significantly. Players suffered from cramps, dehydration, and exhaustion. The Bills went on to lose the game as the clock expired on their final drive down the field. Many factors played into the loss, but it is undeniable the numerous heat-related injuries took their toll.
The Bills were not the only team to boil under the Miami sun. In 2018, the Bears played an October game in Miami that extended into overtime. The weather was sunny and 89 degrees. The Bears moved noticeably slower as the game went on. After the game, former Dolphins head coach Adam Gase acknowledged the heat was an advantage for the Dolphins players because they live in the environment. 
Coach Gase did not acknowledge how the Miami stadium itself is built to further the advantage. The Miami stadium is situated so the home sideline is shaded during game time, giving players an additional break while the visiting team continues to roast in the sun. The traditional argument in weather-related home-field advantages is that both teams experience it equally. The home team is used to the climate and is therefore more accustomed to playing in the conditions. However, the experience is not so equal when one side is positioned for a break that the other does not get.
Depiction of Miami Stadium showing the home sideline shaded – SeatGeek
Advantages like the sideline in Miami are problematic. The advantages can compromise the competitive integrity of games, impact fan sentiment, and disrupt the sports betting market. In situations like Miami, it also threatens player safety.
Sentiment around overtime rules shows that fans care about the skills of the players deciding a game. Bills fans, and others around the NFL, were highly critical of last year’s divisional round between the Bills and the Chiefs that ended in an overtime win for Kansas City. Only a few years prior, Chiefs fans were similarly upset about an identical loss to the Patriots. After continued frustration from fans, the rule was changed to provide both teams the opportunity to possess the ball. Impactful sideline advantages have the same effect as unfair overtime rules. Both can decide a game without consideration to the skill of the players.
Tom Brady in the overtime win against Kansas City – New York Times Ed Zurga/EPA, via Shutterstock
The sports betting industry takes home-field advantage seriously. Home-field advantage is historically accorded at least three points in calculating a point spread. These numbers have decreased in recent years, and new numbers indicate that three points may be an overestimate.  These estimates could be dramatically thrown off if teams begin to design their stadiums with strong advantages.
Player safety is another factor in sideline fairness. Field safety is addressed in some ways by the NFL. All fields must be certified by NFL Football Operations. Part of the certification is a test for stability. The stability test considers how loose the grass is, total grass coverage, and the hardness of the field.  These tests are important because player safety is strongly impacted by field conditions.
Heat also presents a safety concern in the NFL. Since the tragic death of Korey Stringer, the NFL and other sports organizations were prompted to implement stringent safety regulations related to heat stroke. Heat stroke can be prevented through adequate hydration, frequent rest, taking time to acclimate to the climate, and getting in the shade whenever possible.  Considering the safety concerns around heat stroke, stadium design should also take player safety into account.
While the rules lack anything specific concerning sideline amenities, they do allow for the commissioner to act in emergencies. These actions are normally reserved for inclement weather-related hazards. If heat is treated with the same concern as inclement weather like lightning, the Commissioner could act as necessary to ensure player safety. Further, the rules do allow for player benches to be located along the same sideline if needed.
Outside regulations could occur if the league fails to act on this and other safety issues. The league is currently embroiled in a concussion scandal that has many calling for fundamental change in the league.  Players suffering from heatstroke while playing may also raise eyebrows if it continues to happen. Both of these concerns could prompt a historic first intervention by OSHA in the name of player safety. 
Sideline fairness could become a bigger issue in the league if more teams take advantage of this loophole. Teams could look to stop providing heaters and wind blocks in cold weather climates. More teams could move to increase the sun factor in warmer climates. Both of these strategies would be anti-competitive, would take away from the game, and impact player safety. It is important that the league take action to implement explicit rules on sideline amenities, and take action when it is affecting the game.
 https://operations.nfl.com/the-rules/2022-nfl-rulebook/ (Rule 17 §1 Art. 4)(Rule 17 §4).