Europe's top clubs, including some Premier League sides, have held discussions about using six substitutes per game to ease the workload on players.
Sides met at the European Football Clubs' (EFC) general assembly in Rome last week to discuss issues within the game.
It was not officially on the agenda, but clubs had informal, private discussions about utilising 28-man squads - up from the current 25 - and six substitutes.
Manchester City, Liverpool, Manchester United, Arsenal and Nottingham Forest were among those from the Premier League in Italy.
Football's rulemakers, the International Football Association Board (Ifab), would need to recommend any changes first, and it is unclear when, if at all, any changes would be made.
Five substitutes were introduced in the Premier League in May 2020 before football resumed during the coronavirus pandemic.
The league reverted back to three for the 2020-21 season, before five was voted in permanently from the 2022-23 season. An extra substitute is allowed to replace a player with a suspected head injury.
Three extra squad places are seen as being able to reduce the workload on players after threats of strikes.
Last season Tottenham defender Archie Gray was included in 80 matchday squads for club and country, including friendlies, the joint highest in Europe with Real Madrid's 20-year-old midfielder Arda Guler.
Gray, 19, made 48 appearances as Spurs won the Europa League and helped England Under-21s win Euro 2025 in the summer.
Sources close to the Professional Footballers' Association (PFA) have doubts if 28-man squads would help players, given it would not stop them from travelling in a matchday squad or ease mental fatigue regardless of whether they play.
In June Uefa, the EFC, FifPro Europe and European Leagues launched a study to better assess different types of injuries, performance levels and player welfare.
Last month FifPro, the world players' union, released its fifth annual report on the issue, looking at how much players played and travelled in 2024-25.
It wrote: "Even if the player does not end up playing any minutes, they still have to be physically present and fully participate in team preparations, mentally prepare, while often spending time away from home and undertaking international travel.
"As such, these occasions are also part of the player's working time commitments."
The EFC represents more than 800 men's and women's clubs from 55 countries, with Paris St-Germain, Inter Milan and Barcelona among those who attended last week.
The advent of the five substitute rule at the start of the 2023-23 Premier League season has had a big effect on the number of goals scored from the bench.
Only 4.7% of goals came from substitutes in the inaugural Premier League season in 1992-93.
That figure steadily rose but, after 9.8% of goals came off the bench in 2021-22, it jumped to 12.7% when managers had the option to make two extra changes.
After two further seasons of increases it is at an all-time high of 16.1% this campaign.
Between 1995-96 and 2018-19 there were an average of 96 substitute goals per Premier League season.
In the three full campaigns when five substitutes have been allowed, they have scored an average of 146 goals, with that figure set to rise if this season's trend continues.
But have these goals had an impact on the outcome of matches?
The highest figure in a season for winning goals scored by substitutes came in 2023-24 with 36, but overall there has not been a dramatic change in the number of game-changing goals off the bench with five substitutes.
Teams are not always using their full substitute allowance.
Since the new rule was introduced, clubs have made five substitutions in 43% of games.
Between 1995-96 and the start of the Covid-19 lockdown in March 2020, clubs made the maximum three substitutions 59% of the time.