Can see why this thread has been named 'AGAIN'... very old story, eh?
Battery balancing or equalisation is required on any EV with NMC battery chemistry; a 'slow charger' is needed for this and is acheived by any AC charger, not just a 'granny' (that would indeed drive you nuts given the clacial rate). This can happen from 80-90% but as we see, MG recommends from 80% every six weeks or so. Most other manufacturers currently have this 'split' between LFP & NMC on SR vs LR cars (eg Tesla, Ford) & some manufacturers have NMC only models (eg Volvo XC40, C40).
To answer the question about 'proving' this, you can either sit there in the car and observe this when the charging rate drops to a trickle, or, simply look up the stats on a home 7Kw charger if you have one & this shows that decrease in charge level once past 100%; Wallbox Pulsar Plus 7Kw here and this is exactly what the app shows in a graph.
I owned a gen1 ZE EV (NMC) for a couple of years and that's how it worked like clockwork, charging overnight off-peak every two weeks to 80-90%, then to 100% and balance every 6-8 weeks. This was done by the Wallbox app & gave a record of the stats. When doing a battery balance, this awalys took 90mins or so beyond the 100% charge.
All of which is a bit of faffing about (but also applies to other NMC EVs; a bit silly really IMO - we pay a premium for a 'long range' car, but then find this to some degree crippled by the 80% charging rule). I susbsequenlty upgraded to a gen 2 2022 ZS EV SR LFP. What a brilliant thing - no more rubbish about battery charging rules, but also surprisingly much more refined than the gen 1 (suspension, soundproofing, sound system, motor, torque etc). From the same stats on the charger, it is also clear that it does a balance as well beyond 100% but doesn't seem to take all that long.
So I'm inclinded to stick with LFP chemistry, or forthcoming Sodium etc. BTW the only EV that I'm aware of that uses LFP chemistry right across the range is BYD, they're selling like hotcakes in Australia. The Blade battery is used for any and all ranges & the new Seal in particular now must have the longest range of any LFP battery on the market.