Pressing CTRL+A within a text field causes Minecraft to flicker and freeze. Minecraft will remain flickering and frozen until the window is resized, after which the game goes black and remains. No other key combination triggered this behavior.

When all other factors are the same, the issue affects 1.17 and 1.17.1, but not 1.16.5

EDIT: After additional testing, the issue does not affect 21w08b and earlier, does affect 21w10a and later.