Spelling - Oxford English (UK) is wrong

When using the otherwise excellent Brave browser, there are many spellings (using the UK Oxford English Dictionary spelling) that are flagged as incorrect, when they are English (British) standard spellings. The corrections offered are to American spellings. Examples include:

realised (suggested: realized)

The correct spelling is shown here:

This could be that the link above shows the word as ‘realize’ in their UK dictionary, but then underneath the definition states ‘(British realise)’. So perhaps the OED / Lexico is creating the confusion by having the American spelling in the British spelling section.

Whatever the cause, what’s actually being promoted here is the American spellings, not the British ones.