Copy paste the below snippet in your custom css to make your database views appear in different tabs.

/* render database views as tabs */
 
.notion-collection-view-dropdown-content {
    display: flex;
    box-shadow: none;
    align-items: center;
    justify-content: start;
    gap: 30px;
    flex-wrap: wrap;
    margin: 0 auto !important;
 }
 .notion-collection-view-dropdown-content-item-active-icon>svg {
    display: none !important;
 }
 .notion-view-type>svg{
    display: none !important;
 }
 .notion-collection-view-type-title{
    overflow: unset;
 }
 .notion-collection-view-dropdown-content-item {
    padding: 10px 20px 10px 20px;
    border-radius:5px;
    box-shadow:0px 0px 0px 2px black;
    color: white !important;
 }
 .notion-collection-view-dropdown-content-item:focus,
 .notion-collection-view-dropdown-content-item-active {
    background-color:black;
    color: white !important;
 
}
 .notion-collection-view-dropdown-content-item-active>.notion-collection-view-type>.notion-view-type>.notion-collection-view-type-title{
    color: white !important;
 }
 .dropdown {
    display: block;
 }
 
.dropdown-trigger {
    display: none;
 }
 
.dropdown-menu {
    display: block;
    position: unset;
    z-index: 99;
 
}
 .dropdown-content{
    background: unset;
 }
 .notion-collection-view-dropdown-content{
    padding: 25px 0px 25px 0px;
 }
 .notion-collection-header{
    display: flex;
    justify-content: start;
    padding-left: 90px;
    align-items: center;
    margin: 10px 0px 60px 0px;
 }
 .notion-collection-view-dropdown-content {
    display: flex;
    box-shadow: none;
    align-items: center;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
 }