If you choose to leave a WhatsApp group that has become increasingly noisy or irrelevant, the app will post a notification that anybody can see in-chat. It's probably not a big deal in most instances... unless it's a group with relatives or friends who are inclined to ask why you'd left. According to WABetaInfo, WhatsApp is working on an upcoming feature that could prevent awkward confrontations by letting you exit groups without posting a notification everybody could see.
To note, the app will still notify the group admins that you're leaving when the feature becomes available, but everybody else wouldn't know unless you tell them. WABetaInfo first talked about the feature when Meta discussed experimenting with Communities, which people can use to combine separate group chats "under one umbrella with a structure that works for them," back in April. Now, the publication has obtained a screenshot of WhatsApp beta on desktop that shows an exit prompt that reads: "Only you and group admins will be notified that you left the group." Hopefully, the feature will also roll out for WhatsApp on mobile when it becomes available on desktop.
And in case you don't want specific contacts to add you back or to add you into another group chat with them, don't forget that you can always block them from doing so. Under your Privacy settings in Account, you can choose the people who can add you to groups, with the options being "Everyone," "My Contacts" and "My contacts except..." the people you exclude.