Last time I took my bike with Easyjet this wasn’t a stipulation.
It has been at least since I first used them over a decade ago?
I once got asked as it was right on the weight limit, so I said the bike, there was a massive queue so they looked at me funny and waved me off to oversized baggage. I did also have a hold bag though that was only about 8kg.
On another trip on the way back (Malaga) they asked again, and I had a broken arm so had consolidated my hand luggage into the hold and told them 2 weeks of sweaty sports kit. They decided not to check 🤣.
I know one person who flew a couple of times a year and got caught out once. And I’ve been in the airport when people have been having to unpack their bike bags. So it does happen, just fairly rarely. The common denominator on those occasions seemed to be people who had booked no other luggage. i.e. bike bag + hold bag both under the weight limit they don’t care. Turn up with a 32kg bike bag and they seem to ask questions.