DNS TXT Verification records
Today I checked DNSDumpster for my domain and realized that TXT verification records for my email are visible to everyone. Should I be worried? If yes how can I hide them?
Everything in DNS is visible to everyone. Why are you worried about that? And no, you can only remove them, not hide them.
The txt entries are used to authenticate that you own the domain usually.
Email provider X asks to to put a random string of characters in the txt entry because that validates that you have ownership of the domain. Nobody can take that string and do anything with it, and nobody else can steal it by using the entry because service Y will ask for a different random string.