Describe the bug
When adding a button block to the app and opening on the web the block displays the error "This block contains unexpected or invalid content."

Following the blocks suggested resolution strategy turns it into a paragraph block.
Failing example

<!-- wp:button {"className":"wp-block-button__link"} -->
<a class="wp-block-button wp-block-button__link">Button 1</a>
<!-- /wp:button -->

Successful example

<!-- wp:button -->
<div class="wp-block-button"><a class="wp-block-button__link"></a></div>
<!-- /wp:button -->

The issue appears to be related to {"className":"wp-block-button__link"}

To Reproduce
Steps to reproduce the behavior:

1. Add a Button block to a post
2. Save the post
3. Open the same post on the web
4. Block shows a conversion error

Expected behavior
Block should be understood by the web.

Screenshots

App HTML:

Web Conflict:

Web Resolution Suggestion:

Smartphone (please complete the following information):

• Device: Android Pixel 3a
• OS: Android X
• Version: 29

Additional context
Add any other context about the problem here.