After Bayern and United met in the UCL, Henry asked Kane an interesting question in the post-match interview: "Does it bother you that you can't drop deep as much as you used to for Tottenham?" This was in reference to Tuchel asking Kane to hold his position as a target striker more than he did for his previous club because he needed him to stretch the play during the build up of attacks.
Fast forward to EC 24 and that sounds awfully familiar. Only this time, nobody told him to keep his position. Instead, he followed his natural instincts and came short all the time. The same goes for Bellingham and Foden. That lead to the pretty absurd situation that England looked much better in attack after subbing off one of if not the best player (Kane) for a clearly inferior one (Watkins). Southgate could only make it work "indirectly" by pairing the correct profiles of players together but he was unable to provide tactical instructions that create synergies between his star players. That's not a terrible thing per se, lots of international coaches are handling things like this because it is difficult to drill a system into a team within a few weeks. But in the end, he was neither bold enough to bench some of his stars in order to play cohesively nor did he ask them to move in a way that prevented them from occupying the same spaces all the time.
Rooney recently referenced Guardiola as a cause for the boring games at the EC and he isn't totally off, IMO. In a way, Guardiola is highly risk-averse just like Southgate since he only wants his players to make easy low-risk passes. But Guardiola has a clear plan how players should position themselves to progress the ball through the lines and create chances. Southgate's approach isn't nearly as wholistic as this. Guardiola's teams for instance always make runs inbehind and they have the necessary width. He lets his full backs push high or let them roam into midfield areas so that CMs can attack the box. Gündogan for example had scored 30 league goals in his whole career, then went on to score 29 EPL goals over three seasons because Guardiola asked him to make runs into the box after the full backs pushed into a CM role. Stretching the play and providing a threat inbehind is very important for a possession oriented system and Southgate neither fielded players who try this naturally nor instructed the ones he picked to do it anyway. As a result, England had lots of possession against teams that accepted their greater individual quality but knew they lacked the cohesiveness to constantly break down a low defensive block but were completely dominated the moment they faced a strong team - until Southgate subbed in threat inbehind with Watkins.
I think there would have been multiple ways to fix this, either by making tough decisions and prioritizing natural/instinctive cohesiveness over quality (Watkins for Kane) or, what I would have preferred as an England fan) tactical instructions. You can't turn Kane into an Mbappe but you can ask him to hold his position more. Or if he drops into midfield, Bellingham could have been the ideal player to make runs into the vacated space like he does for Madrid. Foden is also a player that played very vertically not too long ago for City. And you could ask your full backs to push up higher, especially with the recovery speed and athleticism of Walker. That would pin the opponent's defense back and would allow Trent in midfield some time on the ball, not exposing his lack of pressing resistancy.
If you ask me, I think it is a testament to the quality of your players that you made it to the final (again). They get criticized a lot but I don't really saw bad performances by any of them. Nobody constantly fecked up promising situations or made the wrong decisions (at least not overaveragely), they simply didn't get into threatening spaces and that is a clear sign that something with the tactics is wrong. Personally, I wouldn't be disappointed if England sacks Southgate and appoints a competent coach although that would IMO drastically reduce our own chances of winning WC 24 - but seeing this amount of talent being wasted by a coach who simply isn't good enough is frustrating even as a neutral.