handling of $dynamicRef on openApi v3.1 spec schema

**What version of Ajv are you using? Does the issue happen if you use the latest version?**
8.2.0
**Ajv options object**

```javascript
{ strict:false }
```

**JSON Schema**

```json
{
"type": "object",
"properties": {
"name": {
"type": "string"
},
"in": {
"enum": [
"query",
"header",
"path",
"cookie"
]
},
"required": {
"default": false,
"type": "boolean"
},
"schema": {
"$dynamicRef": "#meta"
},
"content": {
"type": "object"
}
},
"required": [
"in"
],
"oneOf": [
{
"required": [
"schema"
]
},
{
"required": [
"content"
]
}
],
"$defs": {
"schema": {
"$dynamicAnchor": "meta",
"type": [
"object",
"boolean"
]
}
}
}
```

**Sample data**

```json
{
"name": "limit",
"in": "query",
"description": "How many items to return at one time (max 100)",
"required": false,
"schema": {
"type": "integer",
"format": "int32"
}
}
```

**Your code**

```javascript
const Ajv = require("ajv/dist/2020.js")

const ajv = new Ajv(options)

const validate = ajv.compile(schema);

console.log(validate(data));
console.log(validate.errors);
```
https://runkit.com/seriousme/ajv-dynamicref

**Validation result, data AFTER validation, error messages**

```
false
[
{
instancePath: '/schema',
schemaPath: '#/oneOf/0/required',
keyword: 'required',
params: { missingProperty: 'schema' },
message: "must have required property 'schema'"
},
{
instancePath: '/schema',
schemaPath: '#/oneOf/1/required',
keyword: 'required',
params: { missingProperty: 'content' },
message: "must have required property 'content'"
},
{
instancePath: '/schema',
schemaPath: '#/oneOf',
keyword: 'oneOf',
params: { passingSchemas: null },
message: 'must match exactly one schema in oneOf'
}
]
```

**What results did you expect?**
I expected the validation to succeed.
https://json-schema.hyperjump.io/ says the data matches the schema.

The schema is part of the [OpenApi 3.1 schema](https://github.com/OAI/OpenAPI-Specification/blob/main/schemas/v3.1/schema.json) (which is not under my control)
The data is part of the well known Petstore example
( I created a [v3.1 Petstore example](https://gist.github.com/seriousme/55bd4c8ba2e598e416bb5543dcd362dc#file-petstore-v3-1-json) by taking the v3.0 Petstore example, updating the `openapi` version to "3.1.0" and adding a licence URL)

Validation of the full v3.1 Petstore example against the full 3.1 schema works with:
- [Hyperjump](https://json-schema.hyperjump.io/)
- [jschon for Python](https://github.com/marksparkza/jschon)

Which leads me to think that the issue is not in the schema but in Ajv ;-)

I also tried to resolve the issue by tweaking the schema:
- Replacing `"$dynamicRef": "#meta"` by `"type": [ "object", "boolean"]` solves the issue.
- Replacing `"$dynamicRef": "#meta"` by `"$ref": "#/$defs/schema"` solves the issue as well.
(when applied to the full OpenApi 3.1 schema this lets Ajv validate the full Petstore example as well)
- Removing `/$defs/schema` from the schema still gives the same error.

Hence my suspicion that the problem is caused by the handling of `$dynamicRef` by Ajv

**Are you going to resolve the issue?**
I'm happy to help but I think it requires some quite deep knowledge of Ajv internals.