Vaadin 25: style issues

[javier-godoy]

Describe the bug

Expected behavior

Minimal reproducible example

https://addonsv25-staging.flowingcode.com/whatsappbutton/whatsappbutton

Add-on Version

2.0.1-SNAPSHOT

Vaadin Version

25.0.0-beta5

Additional information

No response

[paodb]

Re-tested with Vaadin 25.0.3. Icon no longer looks misdisplayed but the button keeps not showing the expected style.