Encryption is not enough. Relationship maps (identity derived from who you're associated with). Signal, Telegram, WhatsApp uses your phone number for this association. They also have access to your contact list. Protonmail and Tutanota use your email for this.
WhatsApp uses device fingerprint, so its the same to parent company FB if user is using WhatsApp, Messenger, or FB, or is using whatever login name. It's obvious to them because the device is the same. Also crowd-verified by family all in same location, and who tag people, intersecting locations. WhatsApp may be e2e encrypted.
Signal Has phone number and contact list, so not as much info as WhatsApp perhaps.
Telegram Like Signal.
Protonmail Lots of metadata available. Non-encrypted mail can be read, from insurance agents, schools, utilities, etc. Some people publicize their email address. Interdomain email. (Security people suggest using a protonmail account for only intra-domain [specific purpose] conversation, not for everything, although data-contamination happens from what your contacts are doing).
Tutanota Another email like Protonmail.
Suggestions by security people: Use something like Signal, but only with family (no concern over establishing a relationship map). Have a private email server and use in a limited way, for intradomain conversations. Use 'noIdentity.'