What if there're 2 blocks verified?

[freedomseeker]

Hi I'm new to this community and this is my first post.

I learn that bitcoin always take the longest blockchain for consensus but from time to time there'll be two blockchains in parallel if two miners solved the hash. I want to know if my tx is in one of the chain, and that chain turns out to be the invalid one, does my tx also become invalid and how to make sure my tx is really verified?

Sorry my question may sound dumb. Thanks for answering

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[Xynerise]

No, your question is not dumb.
It explains why bitcoin doesn't have faster block times.

Rarely two blocks are found at the same time but by different miners, when both a broadcast the nodes favor the one with more proof-of-work.
The other block becomes orphaned and the transactions there that were confirmed for a bit become unconfirmed if they're not present in the competing block that was found and they return to the mempool awaiting the next block.

That's hey you're advised to wait for 6 confirmations to accept Bitcoin as finally confirmed in case there is a block reorg.

If you want to read more on this check out Andreas Antonopolous' book Mastering Bitcoin.