Mixing Dot 4 with Dot 5 brake fluid

Just got Dot 4 in there now and was going to do a quick top up with Dot 5.

Will this have any negative effect? Presume the world will not end or the whole system explode.

(More specifically, they don't react and end up with bubbles in the system)...

I think (not SURE!) that dot4 and dot5.1 (which is 99% of the dot"5" you'll encounter in real life) is OK. actual, proper dot5 is apparently a big

While it’s permissible to mix DOT 3, DOT 4 and DOT 5.1 brake fluids, DOT 5 Silicone fluid
cannot be mixed with any other type. If the system is not completely purged before conversion, the mixture may gel and result in very poor braking.