Hi Mateo,
Greetings form Syncfusion support,
We have validated your reported query. We have tried to reproduce the reported issue using the latest Nuget version 18.3.35 and unfortunately we could find any issues with the SfSpinner rendering.
We have improved the Blazor Spinner component with our latest release.
We would like you to review the breaking changes and the release notes regarding the changes we have included in this release from the below location before you upgrade.
Also, can you please try clearing the local Nuget cache and try the same once from your end ?
If you are still facing the reported issue, can you please replicate the issue in the above sample and revert back to us ?. So that we can validate and provide solution at earliest.
Regards,
Indrajith