Please help us help you and fill where relevant: 
Your LimeSurvey version: 6.4.0+231218 
Own server or LimeSurvey hosting: Cloud hosting at hostinger
Survey theme/template: modified theme (extended) from Bootswatch
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We have a website that is available in multiple languages and for each language we Limesurvey imbedded. So to summarize we had the following:

• Bracewijzer.nl (website)
  • wijzer.bracewijzer.nl (limesurvey installation)
• Bracewijzer.be (website)
  • wijzer.bracewijzer.be (limesurvey installation)
• Thuasne-carefinder.de (website)
  • tool.thuasne-carefinder.de

So what we did for each website is to create a separate Wordpress installation under a subdomain. If we tried to put it under one domain (wijzer.bracewijzer.nl for example) we would see error when embedding the form on the other websites not linked under the domain.

With the current hosting it is not possible to install limesurvey under a subdomain of Bracewijzer.be and Thuasne-carefinder.de. Also, think it would be better if I could manage the different tools all from one installation.

I have added a screenshot of an error I get when I have embedded the survey hosted on wijzer.bracewijzer.nl on Thuasne-carefinder.de.

Is there a workaround to fix this issue?

In case you are wondering, I have put IFrame embedding allowed: on Allow

Any help would be much appreciated!

You can use same DB with different hosting

Set the url of the cookie doifferent for each server

www.limesurvey.org/manual/Optional_settings/en#Request_settings

'domain' => '.bracewijzer.nl',

for CRSF and SESSION.