A fixed-odds betting terminal is a type of slot machine. But unlike other categories of slot machine, it was (at one time) allowed a maximum bet of £100 and a maximum payout of £500. The RTP was around 95%, but allowing such a large maximum bet meant you could easily lose a lot of money, very quickly.

In 2019, the regulations changed to make the maximum bet £2 (50 times lower), in line with most other slot machines.

https://www.gamblingcommission.gov.uk/authorities/guide/page...