Hmm, I feel like the details might depend slightly on what exactly is meant by 'toppy burnout' but broadly, I'd say open communication is probably the key.

It's fine for you to say when you're not in a mood or headspace to want to engage in TTWD as a top at any given time or signal when you need a break, or need to delay something until another time.

I am a switch, but find it a little bit more energy to enter my 'toppy headspace'. I'm basically always up for being the bottom in any given situation, but it takes slightly more specific mood or set up circumstances for me to feel enthusiastic about being the tip.

One thing that might help you is to have a signal word (basically a type of safeword) or similar to indicate when you're not up for being 'bratted' or being too much in 'toppy mode' and need a break.

One thing I have seen happen variously between many different people and including myself with others in the past is this sort of playout:

Bottom: does or says something bratty

Top: Tells them to stop it

Bottom: Interprets it as scolding as in 'playing along' and thinks they're in the clear to continue. Doesn't realise the top has actually had enough and/or would like it to stop.

Top: Becomes irritated

Both: irritation and upset.

I have seen cases where the top genuinely thinks they're being clear they mean it seriously but the bottom legitimately can't tell. (I've also seen the reverse where the bottom is trying to express something seriously and the top interprets it as bratting).

I think a lot of this can be headed off by there being a signal word to make it clear you're communicating 'outside of role' as it were. You're ACTUALLY asking them to stop, not scolding them in that TTWD way we enjoy.

It could even be as basic as saying a straightforward phrase that makes it clear like, "I am not feeling in a toppy headspace right now"

Personally, I quite like the idea of prefacing something with a safeword such as 'yellow light' (or 'red light' if more serious, or depending on what safewords you use and how) to make it clear you mean what you say 'for real' and not either as a way or bratting or scolding (could be used by the top or bottom).