Well I think to problem is more the power of the Thompson Upgrade which is incredible, according to https://coh2db.com/stats/#, close range (lower than 10), Thompson (took from rangers squad since they are 5 man squad) has 24 DPS while de MP40 has 15, plus the MP40 has bigger reload time and smaller burst. For comparison, a squad of Panzergrenadier with STG44 has only 15 DPS close range.
While this upgrade was only on paratroopers/rangers/assault guard there was no problem because it's performance fit the elite-infantry role, but such upgrade is now on Assault section (UKF) which are the british counterpart of Assaultgren and therefore outscale them hard.
there are at least 3 versions of the Thompson:
One for officers
One for Cav riflemen
One for Ranger/paras