For anyone playing Career mode, my further update after seriously tweaking sliders and other game settings.
Playing on anything above World Class difficulty breaks the game completely. AI on all settings in FIFA 23 is more aggressive, both in defence and in attack, this becomes unbearable on Legendary or Ultimate difficulty and pushes the game into a terrible goal fest runaround I experienced in the beginning. This may be changed as they update the game, but so far I've only had balanced games on World Class, anything above is hopeless. Defending on Classic settings is also unadvisable. If you use the doubling on a player feature, your other uncontrolled players are not to be relied on, AI will ping around you and score every single time. Name of the game is to be compact. To defend with any purpose, use tactical defending, don't lunge too often, contain players as much as you can and cut passing lanes where possible. Also sliding tackles are more useful than before, but as always caution is advised as the opponent can turn on a dime and earn you a red card.
There is a setting accessed from the main game menu, not inside the Career mode, to tweak the referee strictness. I strongly advise using at least Strict, if not Very strict, therwise they'll constantly barge you off the ball unpunished. Also, I found the game to be horrible on Slow speed. Though this was my preferred option for many years, I'm now playing on Normal but reducing Sprint speed via sliders to 20 or below, and Acceleration to between 30-40. Players just move weirdly and stutter on Slow speed setting and it breaks the flow of the game. Passing, building attacks and shooting is actually improved this year. First of all, not all players sprint instantly and various sprinting styles are an interesting addition. I have a CB that is fast as anything, but he does take an age to get going with his long strides. If a ball breaks and he has some open space to run into I can use him to open the pitch completely and even cross into the box. But if I try it with few opposition players around, they'll nick the ball off him by the time he gets going. Once I figured this out and made a mental note of it - it's actually a fun feature. Same applies to nippy, wingers that are better utilised using short bursts of pace to break through lines, but may not have the top speed to get ahead of a CB in a long foot race. It's good, adds a layer of genuine distinctiveness to players that is sorely missing from FIFA. There is also some semblance of momentum this year to player movements, so just direction and speed shifting is a viable way of dribbling through opposition in a more natural way, instead of full tilt sprint + skill moves. I don't know any skill moves anyway, so can't comment on them. Shooting is a bit too fast, so best to tone it down via sliders.
Still some new fucntions I haven't explored, but I've managed to get a better game of football than out of the box. Hope it helps anyone playing Career mode.