Slot <template> not working when its name starts with an underscore (_) since v3.5.14

[laurens94]

Vue version

v3.5.14 - v3.5.17

Link to minimal reproduction

https://play.vuejs.org/#eNq9Vd9P3DAM/les7gEJHa2mbS+3gsbuhrYJhjSQ9rAiyLW+u0CaVElaOCH+9znN9ReFaUzTpD609mf7s+t8uQ8OiyKsSgymQWwxLwSzeJBIgPgjM3jMNqq09TdZGj9Ue3y5nwRMbmZKZtxyJWdrTG8+o8YfXIi5SgJ4pZnMVG6EspLlPmmdpmhfAQ4NCCVXwAzcIjCNkDYZmRAb0Cgz1JwQds0NuGQTekVArZUGlaalNmG80L2c5+R2QMgUGrljASuUsGYVglWAd9xY4LLOkqq8UBKlDVt2UUMvjgbzANiaz8rFrAnrmmpn88pyK7puyZXxCozdCKSRpUooPYWVRpRJcHBVg6+gjb5V+sbEEYV0qfs8nqh3mZWauYH9ac024AV1vWHUehwNtuQR1dikmhcWBJMr4mENbYVBW/oJc0qkLfRzwlKrHHbCQSG3nTvvexFdyRbfmRq0w9Mq0a/+zZbCPlhdIsHjyHMlZsGEmFLokq/Ca6MknYx7l80NMi+4QH1auFzUzRRqj/PZTYG15WcSVNzinqlWe0Ix2t4kmBDAGaNUcOrIGz7UIVGZs5wnwcWkzcT0CgkzpfdPZ9/wzuEbZ2lwjksu8UjpmWDGHHEUWV3YddLicpWVAp9J4p3f0ShRuk48bFHKjJrr4YzVPK2ZDHJfmzsfUWg0qCsq04WoUqd4wopRFGGVqPArTfSkJTdAcALQ6mTePe4Jjfd8kRa1GlcQfOF/wHaBR5070/z0JAn8Zzdyc8OLY76ot2NMXCk75zQX13IY+eiH2k2cZSrKrO5lW5ey6TTa3Y12Q7fwXY3Gmj1jt26sYzPtsy95kcgHt9e0n8N1H0t3d4zjWgid/tIBHAoySQFtPX30oX1TIwcvONXDY/T4FI+J9tnVUkiktmyeUDCNGfnP3UVAj9PvDJesFNbLPZ1ZW4sIXQxbYa1vht4d42Ka/ik705buHW7XJBJA64+aDr5Gf8O02thcI04jw04j20mNOmkF9p9100n2f+nor//4ZUUFiSb96Tfhu/D12+DhF76Uxyk=

Steps to reproduce

It seems this issue needs the following conditions to arise:

• Have some templates/slots that start their name with an underscore (_)
• The component that contains the templates/slots (SubComponent.vue), is placed in the template of another component (BaseLayout.vue) and is a sibling of a conditionally rendered template for a slot of BaseLayout.vue.

What is expected?

The same behavior as in Vue v3.5.13: the template is being rendered for _slot2

What is actually happening?

The default slot content is being rendered and not replaced with the template content.

Any additional comments?

Since Vue v3.5.14 this issue occurs. As a workaround I locked the version to v3.5.13.