Error in displaying an override for

PHP 8.4.22
Joomla 5.4.6
CB 2.11.0
CB Subscriptions 4.9.0
database MySql 8.0.30

Dear support,

If I change in CB Plugin 'Default language 'English)' or in Plugin 'nl-Be' in the overrides the text for BUY_831a28 from
Pay
to
<span style="font-size: 18pt; ">PAY</span>
or to actually any other html coded text, the html is not accepted, in stead on the frontend it showes the plain html code:
<span style="font-size: 18pt; ">PAY</span> itself.

I used this kind of editing for many other overrides, where it works perfectly.
Can you take a look at this please? 
Thank you.

You can't put HTML in that string. Increase its font size using CSS rather than inline style HTML. You can add custom CSS to CB using the CSS overrides feature shown below.

www.joomlapolis.com/blog/kyle/18711-template-css-overrides-made-easy