The idiom used when a bad situation is not fully resolved and can escalate easily again

Is there an idiom or expression in English to describe a situation where a bad situation is not fully or correctly resolved and it can happen again, may be even worse.

For example, when talking about people's feeling/wrath regarding the government that recently suppressed their protests instead of answering to their requests. in such a situation, in Persian, we say people are fire under the ashes.

Thank you

The verb smoulder is, correspondingly, often used metaphorically here.

smoulder verb [I] (PROBLEM) If a problem or unpleasant situation smoulders, it continues to exist and may become worse at any time:

The dispute is still smouldering, five years after the negotiations began.

CED

(The literal definition is 'to burn slowly ... without flames'.)

Be a (ticking) time bomb may suggest the idea you are describing:

A person, thing, or situation that can at any moment cause much havoc or result in a disastrous outcome.

• I'm telling you, this dirty money we're using to finance the campaign is a ticking time bomb! If anyone were to investigate how we got it, we'd all go to jail! Jenny's attracted to men who exude an air of danger, and her new boyfriend seems like a time bomb.

(The Free Dictionary)

'Kick the can down the road' is an expression that conveys the concept of a problem accompanying one on one's journey, and that by one's own deliberate attachment to it, rather than resolving the matter and leaving it behind as one progresses.

An interesting comment and history of the expression is recorded in Merriam Webster.

However, by kicking the can down the road again at least we go another year without having to pay for our out-of-control national debt.

News Times- January 3rd 2020