Can I use
?

PNG alpha transparency

- REC

Semi-transparent areas in PNG files

Chrome

  1. 4 - 110: Supported
  2. 111: Supported
  3. 112 - 114: Supported

Edge

  1. 12 - 110: Supported
  2. 111: Supported

Safari

  1. 3.1 - 16.2: Supported
  2. 16.3: Supported
  3. 16.4 - TP: Supported

Firefox

  1. 2 - 110: Supported
  2. 111: Supported
  3. 112 - 113: Supported

Opera

  1. 9 - 94: Supported
  2. 95: 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. 111: Supported

Safari on iOS

  1. 3.2 - 16.2: Supported
  2. 16.3: Supported
  3. 16.4: Supported

Samsung Internet

  1. 4 - 19.0: Supported
  2. 20: Supported

Opera Mini

  1. all: Supported

Opera Mobile

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

UC Browser for Android

  1. 13.4: Supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 111: Supported

Firefox for Android

  1. 110: 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