This is unsubstantiated. I worked in the UK for several years (IT worker) and met a few people who had worked in China (teaching English, among other things) and they had zero issues getting visas.
It's one of those cases where you hear stories about visas (you hear a LOT from expats, it's just one of those things) and the rule is - until you see it written on an official site, don't believe it.
It's possible that some rumours have arisen from Britain still having some restrictions on Chinese investors.
Statements like this (quote from article linked):
Mr Liu said that prominent Chinese businessmen are still being
rejected when they apply for visas to come to the UK.
He said that many were rejected and unable to attend a recent business
leaders’ summit but that he did not know the “real reason” their visa
applications were turned down.
also don't help matters. If he actually asked them, he could find out why and it could be for all sorts of reasons - incorrect applications, failure to provide evidence of actual business transactions, failure to show funds, exit tickets etc, but instead, more unsubstantiated statements.