Hey, @Iñaki59 Welcome to Spotify Community and thanks for reaching out here!
I hope you don't mind I'm answering in English...
First of all, have in your mind that some devices may be recognized by your Spotify Connect because they may be connected to the same WiFi network. If it's the case here, you can get more information about how to disable this option here.
If these devices you don't recognize aren't on your own WiFi network but persists in appearing on your Spotify Connect, maybe your account was compromised, as mentioned by @Letmedrum. This way, you can follow some steps to remove the devices and recover your account. To remove these devices from Connect, you need to:
1. Find the device and tap on the three-dots menu
2. Then, select the option 'Forget this device'
After that, you need to stop the access to your account from anyone else. You can follow this guideline to recover the security of your account.
If you have any other further questions or need more help, let me know! I'd love to help!
Best Regards, hezorg
LuanRock Star 14
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