Are these doors on your own home? If not or you’re not overly bothered by appearance. Replace the combined strips in the door/frame rebate with an intumescent strip that has no brush seal. Then fit a smoke seal to the door stop/ frame ( just like an old fashioned draught brush). If its an entry door to a flat adding a drop down seal at bottom of door does wonders for sound transmission and draughts.

If its on doors where appearance is more important, seals/strips only usually come adrift because the either the rebates are too big for the strip and or the door is fitted a little to tight to the frame and the opening and closing on a tight brush works the strip loose or damages it. The allowable gap between door and frame on a fire door is 2-4mm. Most brushes need nearly all of that. If you’re gaps are less then have a look round for a strip with a shorter brush. Or if the strips are in the frame/ lining , reduce the size of the door ( so long as you take off no more than the specified allowance) be careful on the head of the door , some don’t allow trimming and instead you’d need to drop it onnthe hinges.