I've flown nonstop from the UK to Schengen land over 20 times this year. Immigration in Norway in January asked questions about a return ticket, proof of funds, etc... but Oslo in January when everyone needed a compulsory Covid test on arrival was far from busy and there was capacity in the system to do these immigration checks. Since then, checks on arrival into Schengen seem no different to pre Brexit. That includes arriving in Malaga on a bank holiday Saturday
I would call 100% bullsh*t to anybody who blames post Brexit arrival checks into the EU for UK passport holders as a reason for any problems.