Have you got Hi8 Video Tapes in your Home Movies or Archive?
Check & see if they are Fuji. They seem to be very susceptible to Tape Mould. This is the third lot in as many months. They bind & grow mould under the spool
Get them Digitised, quickly
These are in particularly bad shape.
PS - my quote of £25 per tape for hand cleaning was apparently “excessive”🤷♂️