Yes, I do have a X-T30. At this moment, I have a Sandisk Extreme Pro 170MB, 64 gb card in it that works just fine for what little video I record using that camera. But I have a selection of other cards that save video files also just fine, including Transcend and Lexar. But they are all rated as being fast enough for 4k recording, the slower cards made by those same companies can only record 640 or 1080p not 4k. The rating matters.

I am using a sandisk extreme. do you have this camera? which memory card do you use?

Which sd card are you using? The ones listed on this site are decent: https://www.camera-rumors.com/best-memory-cards-for-fujifilm-x-t30/ but as long as your card meets the minimum requirements, it should be okay. Did you try using a different card?

Are you joking? X-T4 does not have a built-in flash.

It's like if the minimum amount of minutes available to record a video is 3/4 minutes.   I never had this problem with any othe camera. The SD card is empty so there is plenty space