Can I use
?

PNG alpha transparency

- REC

Semi-transparent areas in PNG files

Chrome

  1. 4 - 118: Supported
  2. 119: Supported
  3. 120 - 122: Supported

Edge

  1. 12 - 118: Supported
  2. 119: Supported

Safari

  1. 3.1 - 17.0: Supported
  2. 17.1: Supported
  3. 17.2 - TP: Supported

Firefox

  1. 2 - 119: Supported
  2. 120: Supported
  3. 121 - 123: Supported

Opera

  1. 9 - 103: Supported
  2. 104: Supported

IE

  1. 5.5: Not supported
  2. 6: Not supported (but has polyfill available)
  3. 7 - 10: Supported
  4. 11: Supported

Chrome for Android

  1. 119: Supported

Safari on iOS

  1. 3.2 - 17.0: Supported
  2. 17.1: Supported
  3. 17.2: Supported

Samsung Internet

  1. 4 - 22: Supported
  2. 23: Supported

Opera Mini

  1. all: Supported

Opera Mobile

  1. 10 - 12.1: Supported
  2. 73: Supported

UC Browser for Android

  1. 15.5: Supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 119: Supported

Firefox for Android

  1. 119: Supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: Supported

KaiOS Browser

  1. 2.5: Supported
  2. 3: Supported

IE6 does support full transparency in 8-bit PNGs, which can sometimes be an alternative to 24-bit PNGs.

Resources:
Wikipedia