Championship leaders Burnley have been asked for their observations by the EFL after making six changes to their starting line-up for a trip to Reading.
The Clarets had already confirmed promotion to the Premier League before their 0-0 draw with the Royals, who are in a relegation battle.
Huddersfield Town, who are also fighting to avoid relegation, contacted the EFL to query the number of changes.
EFL regulations say full strength sides must be fielded in league matches.
However, it is thought the Clarets are not likely to face any punishment.
The regulations also state that "from the fourth Thursday in March, any team sheet for a league game should include at least 10 outfield players who featured on the team sheet for the league game before".